Doctor of Philosophy / Department of Chemistry / Eric A. Maatta / The thesis focuses on the design and synthesis of novel organoimido delivery reagents capable of forming bimetallic polyoxometalate (POM) hybrids, and their use in the assembly of bimetallic hexamolybdate derivatives. These delivery reagents have been designed thoughtfully and separate organic moieties have been selected for coordinating to both the POM cluster and the second metal atom. A series of three ligands [4-aminopiperidine, 4-(4-aminophenyl) piperazine, and 4-(4-aminophenyl) piperidine] were selected and used to synthesize the dithiocarbamate metal-coordinating ligands, which in turn were used for preparing the corresponding metal (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag) complexes. All the complexes were characterized by infrared spectroscopy (IR). Reported routes were followed for the covalent grafting of these metal complexes onto hexamolybdate. But, the poor solubility of these metal complexes was found to be a major stumbling block in our endeavors to synthesize the dithiocarbamate based polyoxometalate hybrids. The observed poor solubility of metal dithiocarbamate complexes was overcome by synthesizing [potassium(I) tris(3,5-diphenylpyrazole)borate] and [potassium(I) tris(3,5-dimethylpyrazole)borate] via thermal dehydrogenative condensation between tetrahydroborate and the respective pyrazole molecule. A series of corresponding transition metal (M = Co, Ni, Cu, Mn) complexes of tris(3,5-diphenylpyrazole)borate and tris(3,5-dimethylpyrazole)borate were synthesized, and characterized by IR and UV-visible spectroscopy, and single crystal X-ray diffraction. The single crystal structure of [manganese(II) (tris(3,5-dimethylpyrazole)borate)2] turned out to an outlier as it displayed the formation of a bis-complex, thus having no substitutable anion for further reaction with dithiocarbamates. Thereafter, a series of metal dithiocarbamate complexes of these [hydrotris(pyrazolyl)borates] (M = Co, Ni, Cu ) were prepared using [sodium 4-aminopiperidyldithiocarbamate] and were characterized by IR and UV-visible spectroscopy. A remarkable improvement in the solubility of these metal dithiocarbamates in organic solvents was observed. Furthermore, attempts to covalently graft these complexes onto hexamolybdate cluster were undertaken, and found to be unsuccessful possibly due to the strong oxidizing nature of PPh[subscript]3Br[subscript]2 and hexamolybdate. Although, we were able to successfully tailor the solubility of the dithiocarbamate complexes to suit our needs, our efforts to achieve the primary goal of synthesizing dithiocarbamate based polyoxometalate hybrids have so far been unsuccessful. A series of three pyridyl based ligands i.e., 3,5-di(pyridin-2-yl)-4H-1,2,4-triazol-4-amine, 4-(pyridin-4-ylethynyl)aniline and 4-(pyridin-3-ylethynyl)aniline were synthesized and characterized. Covalent attachment of these ligands to hexamolybdate were attempted following various well-known routes. Although, no evidence of covalent attachment of 3,5-di(pyridin-2-yl)-4H-1,2,4-triazol-4-amine to hexamolybdate was observed, the covalent grafting of 4-(pyridin-4-ylethynyl)aniline and 4-(pyridin-3-ylethynyl)aniline to hexamolybdate cluster was successfully achieved. Characterization of these novel organic-inorganic hybrids was done using IR and NMR spectroscopy as analytical tools. Attempts have been undertaken to obtain single crystals of these hybrids. Also, a novel route involving halogen bonding as a purification and separation technique for pyridyl functionalized hexamolybdate hybrids is also being explored. The novel acetylacetonate moiety has been explored as an imidodelivery reagent for synthesizing hexamolybdate covalent hybrids, wherein [3-(4-((4-aminophenyl)ethynyl)phenyl)-4-hydroxypent-3-en-2-one] ligand has been successfully synthesized and characterized. Traditional methods along with unconventional methods such as heating at elevated temperatures and microwave reaction conditions, have so far proved to be unsuccessful in the synthesis of the hybrids. A series of the corresponding metal complexes have been synthesized and characterized, where the ligand and its corresponding copper(II) complex have been characterized by single crystal XRD. In the crystal structure of the copper complex, the metal ion sits in a slightly distorted square-planar pocket, where no coordination to the -NH[subscript]2 group is observed, which highlights the potential of using it as an imidodelivery reagent.

Little attention has been given to the formation of the putative PdL2 species required for Pd-catalyzed cross-coupling reactions. Active species are generally difficult to store due to air-sensitivity and are therefore formed in situ at unknown rates and in unknown yields via a variety of palladium precatalysts. Commonly employed Pd(0) and Pd(II) precatalysts are often relatively ineffective because they generate only low concentrations of the bis(phosphine) species PdL2 under most reaction conditions. This thesis describes the use of the easily synthesized and easily handled Pd(η3-1-Ph-C3H4)(η5-C5H5) (I) as a superior precursor than any other documented system for the in situ formation of PdL2. Rapid and quantitative formation of active catalyst solutions allow us to demonstrate that I is also the best precatalyst known for PdL2-catalyzed crosscoupling reactions. We discuss the Suzuki-Miyaura reaction of 4-bromoanisole with phenylboronic acid and demonstrate that, under mild reaction conditions, higher initial rates and higher conversions with I can be obtained compared with other common precatalysts (Pd(OAc)2, Pd(PPh3)4, Pd2dba3, etc.) containing a variety of phosphine ligands. This methodology has also been extended to other cross-coupling reactions, as we demonstrate that higher initial rates and higher conversions with I can be obtained for a variety of Mizoroki-Heck arylations and Buchwald-Hartwig aminations. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-06-25 11:53:06.75

by Chi-Hang Lee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 71-80). / Abstracts in English and Chinese. / ABSTRACT --- p.i / ACKNOWLEDGMENT --- p.iv / TABLE OF CONTENTS --- p.v / LIST OF SCHEMES --- p.vii / LIST OF FIGURES --- p.viii / LIST OF TABLES --- p.x / ABBREVIATIONS --- p.xi / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Discovery of Phthalocyanines --- p.1 / Chapter 1.2 --- Synthesis of Phthalocyanines --- p.4 / Chapter 1.2.1 --- Metal-Free Phthalocyanines --- p.4 / Chapter 1.2.2 --- Metallophthalocyanines (MPcs) --- p.5 / Chapter 1.2.3 --- Sandwich Complexes (MPc2) --- p.7 / Chapter 1.2.4 --- Tetra-Substituted Phthalocyanines --- p.8 / Chapter 1.2.5 --- "2,3,9,10,16,17,23,24-Octa-substituted Phthalocyanines" --- p.11 / Chapter 1.2.6 --- "1,4,8,11,15,18,22,25-Octa-substituted Phthalocyanines" --- p.12 / Chapter 1.3 --- Mechanism for Phthalocyanine Formation --- p.14 / Chapter 1.4 --- Purification of Phthalocyanines --- p.16 / Chapter 1.5 --- Characteristics of Phthalocyanines --- p.17 / Chapter 1.5.1 --- Electronic Structure --- p.17 / Chapter 1.5.2 --- Absorption Spectra --- p.17 / Chapter 1.5.3 --- X-Ray Diffraction Studies --- p.19 / Chapter 1.6 --- Applications of Phthalocyanines --- p.20 / Chapter 1.6.1 --- Colorants --- p.20 / Chapter 1.6.2 --- Photodynamic Therapy --- p.21 / Chapter 1.6.3 --- Catalysis --- p.22 / Chapter 2 --- Results and Discussion --- p.23 / Chapter 2.1 --- "Preparation, Spectroscopic Properties, and Structure of Phthalocyanines Substituted with Four 2,4-Dimethyl-3- pentyloxy Moieties" --- p.23 / Chapter 2.1.1 --- Synthetic Studies --- p.24 / Chapter 2.1.2 --- UV-Vis Spectra --- p.28 / Chapter 2.1.2.1 --- Effects of Metal Center --- p.28 / Chapter 2.1.2.2 --- Effects of Substituents --- p.30 / Chapter 2.1.2.3 --- Effects of Concentration --- p.30 / Chapter 2.1.2.4 --- Absorption Spectra of MnClPc(OC7H15)4 (10) --- p.34 / Chapter 2.1.3 --- 1H NMR Spectra --- p.35 / Chapter 2.1.4 --- Structural Studies --- p.38 / Chapter 2.1.4.1 --- Molecular Structures of ZnPc(OC7H15)4 (3) and CoPC(OC7H15)4 (5) --- p.39 / Chapter 2.1.4.2 --- Molecular Structure of MnClPc(OC7H15)4 (10) --- p.41 / Chapter 2.2 --- Formation and Crystal Structures of Novel Inclusion Complexes of Phthalocyanines and Oxalic Acid --- p.43 / Chapter 2.2.1 --- 1:1Complex with Metal-free Phthalocyanine (8) --- p.43 / Chapter 2.2.2 --- 1:1Complexes with Palladium Phthalocyanine (4) --- p.49 / Chapter 2.2.3 --- Conclusion --- p.51 / Chapter 2.3 --- Cerium Promoted Formation of Metal-Free Phthalocyanines --- p.52 / Chapter 2.3.1 --- Introduction --- p.52 / Chapter 2.3.2 --- Preparation of Metal-free Phthalocyanines --- p.52 / Chapter 2.3.3 --- Conclusion --- p.58 / Chapter 3 --- Experimental --- p.59 / Chapter 3.1 --- General --- p.59 / Chapter 3.2 --- "Synthesis of 3-(2,4-dimethyl-3-pentyloxy)phthalonitrile (2)" --- p.60 / Chapter 3.3 --- "Synthesis of ZnPc(OC7H,5)4 (3 and 6)" --- p.61 / Chapter 3.4 --- Synthesis of PdPc(OC7H15)4 (4 and 7) --- p.62 / Chapter 3.5 --- Synthesis of CoPc(OC7H15)4 (5) --- p.64 / Chapter 3.6 --- Synthesis of H2Pc(OC7H15)4 (8) --- p.64 / Chapter 3.7 --- Synthesis of MnClPc(OC7H15)4 (10) --- p.66 / Chapter 3.8 --- General Procedure for the Cerium-Promoted Cyclization of Phthalonitriles --- p.67 / Chapter 3.9 --- X-ray Crystallographic Analyses --- p.69 / Chapter 4 --- REFERENCES --- p.71 / APPENDIX A lH and13 C̐ưث1H} NMR spectra / APPENDIX B X-ray Crystallographic Data

The aim of the work described in this thesis was to develop a more extensive knowledge of the chemistry of neptunium compounds by making rare, air- and moisture sensitive, low formal oxidation state neptunium compounds with full structural and synthetic characterization. The thesis contains three results chapters. Chapter one introduces neptunium chemistry as a background to the results presented. The first review on the molecular non-aqueous neptunium chemistry is provided and the literature reports to date discussed in the context of this. Chapter two describes exploratory synthetic and structural investigations of the organoneptunium complexes supported by the cyclopentadienyl anion, Cp = (C5H5)-, and the (trimethylsilyl)cyclopentadienyl anion, Cp' = (C5H4[Si(CH3)3])-. The syntheses of [Np(Cp)3]n and Np(Cp')3 complexes are detailed and the effect of the trimethylsilyl group of the ligand on the structure and reactivity have been investigated. Complexes were characterized by single crystal X-ray diffractometry, NMR and ATR(IR) spectroscopy. Both organoneptunium complexes were studied in reactions designed to expand the neptunium redox envelope. Notably, the complex Np(Cp')3 is reduced by KC8 in the presence of 2.2.2-cryptand to afford a product assigned as neptunium(II) complex, K(2.2.2-cryptand)[Np(Cp')3] that is thermally very unstable above approx. -10 ºC, in direct analogy to previously reported uranium, thorium and lanthanide complexes of the general formula, K(2.2.2-cryptand)[M(Cp')3]. The reaction between Np(Cp)3Cl and KCp in THF afforded the unanticipated K[NpIII(Cp)4] product as a result of a single-electron reduction presumably arising from Np–C σ-bond homolysis reactivity. This behaviour appears to be unique amongst the actinides for the An(IV)/An(III) redox couple. Chapter three focuses on oxo-bridged homo and heterometallic complexes. The reaction of NpCp3 with dioxygen afforded not only the simple oxide, (μ-O)[An(Cp)3]2, but also a small quantity of the unexpected new trinuclear oxo- neptunium(IV) compound [{(Cp3Np)(μ-O)}2{Np(Cp)2}], which interestingly contains the rare C2v-symetric [An(Cp)2]2+ structural moiety. This oxo-bridged environment is not paralleled in uranium chemistry. The two isostructural oxides, (μ-O)[An(Cp)3]2 (An = U, Np), allow a comparative study of the magnetic exchange phenomena between the two actinide centres demonstrating an exceedingly strong antiferromagnetic coupling, which is largely independent of the communicated Kramers NpIV (5f3, 4I9/2) or non-Kramers UIV (5f2, 3H4) ions. To design heterobimetallic systems, the uranyl(VI) complexes, [(UVIO2)(THF)(H2L)], supported by the calix[4]pyrrole Schiff base macrocycles, H4LOct and H4LEt, were singly-reduced to uranyl(V) with either of the actinide complexes Np(Cp)3 or U(Cp)3, affording isostructural [(Cp3)AnIVOUVO(THF)(H2L)]. Preliminary investigations of the magnetism of the AnIV-O-UV are reported, although their analysis gave counterintuitive results. Chapter four explores the redox chemistry and molecular and electronic structure of neptunium(III) complexes of the doubly deprotonated trans-calix[2]benzene[2]pyrrole, H2(LAr), macrocycle which has a unique π-bonding potential and conformational flexibility. Interestingly, the reactions with neptunium(IV) chloride yielded mono- and dinuclear neptunium(III) complexes, [(LAr)NpCl] and [(LAr)Np2Cl4(THF)3], with a subsequent elimination of the ligand radical; both complexes adopted η6:κ1:η6:κ1 bis(arene) sandwiched structural motif. In a direct analogy to the redox behaviour occurring in the salt metathesis between Np(Cp)3Cl and KCp, the spontaneous reduction derives from the favourable Np(IV)/Np(III) redox system. The reduction of complex [(LAr)NpCl] with NaK3 in DME produces near-black solutions consistent with [NpII(LAr)(DME)] that in the absence of excess NaK3 gradually convert to the metallated (LAr-H)3- neptunium(III) complex, [K(DME)(LAr-H)NpIII(OMe)]2, featuring the actinide centre bound with a ‘metallocene-type’ geometry provided by the two η5-bound pyrrolides of the ligand. The neptunium(III) compounds were characterized in the solid state by single crystal X-ray diffractometry, ATR(IR) spectroscopy and in a solution by NMR and UV-Vis-NIR spectroscopy.

This Thesis is concerned with the synthesis of post-metallocene group 4 amidinate complexes as pre-catalysts for the polymerisation and oligomerisation of α-olefins. Activation of half-sandwich group 4 amidinate complexes with 1,3-conjugated dienes is also investigated and their underlying chemistry is explored. <strong>Chapter 1</strong> introduces homogeneous Ziegler-Natta catalysis, with a specific focus on group 4 compounds. A review of metallocene and post-metallocene complexes of group 4 will also be presented and their behaviour in olefin polymerisation will be discussed. <strong>Chapter 2</strong> describes the synthesis and characterisation of _K1-amidinate supported titanium complexes. Base-free activation of the titanium cyclopentadienyl-amidinate dialkyl complexes will be investigated and the resulting cationic species will be further explored with commonly applied trapping agents. The synthesis and characterisation of new titanium cyclopentadienyl-amidinate diene complexes and their corresponding tri(pentafluorophenyl)borane-activated zwitterionic compounds will also be described and their performance in the co-polymerisation of ethylene and propylene will be discussed. <strong>Chapter 3</strong> explores the addition of 1,3-conjugated diene reagents to titanium cyclopentadienyl-amidinate and guanidinate alkyl cations. Mechanistic and computational studies of allyl and diene formation will also be described. The polymerisation capabilities of the newly formed complex will be discussed and compared to previously reported dialkyl complexes. <strong>Chapter 4</strong> describes the synthesis and characterisation of aminopyridinato titanium complexes and _K1-_K2-bis(amidinate) titanium complexes. The activation chemistry of the newly formed dialkyl complexes will be investigated. Furthermore, the synthesis of a new bis(aminopyridinato) titanium complex will also be discussed alongside their activity in EPM and EPDM polymerisation. <strong>Chapter 5</strong> describes the performance of the aminopyridinato titanium complexes (synthesised in Chapter 4) in EPDM polymerisation. The sensitivity of the aforementioned complexes towards hindered phenols will also be discussed and their behaviour in ethylene oligomerisation will be explored. <strong>Chapter 6</strong> presents full experimental procedures and characterising data for the new complexes reported in this Thesis.

No description available.

Organic and organometallic electronic materials continue to attract considerable attention among researchers due to their cost effectiveness, high flexibility, low temperature processing conditions and the continuous emergence of new semiconducting materials with tailored electronic properties. In addition, organic semiconductors can be used in a variety of important technological devices such as solar cells, field-effect transistors (FETs), flash memory, radio frequency identification (RFID) tags, light emitting diodes (LEDs), etc. However, organic materials have thus far not achieved the reliability and carrier mobility obtainable with inorganic silicon-based devices. Hence, there is a need for finding alternative electronic materials other than organic semiconductors to overcome the problems of inferior stability and performance. In this dissertation, I research the development of new transition metal based electronic materials which due to the presence of metal-metal, metal-?, and ?-? interactions may give rise to superior electronic and chemical properties versus their organic counterparts. Specifically, I performed computational modeling studies on platinum based charge transfer complexes and d10 cyclo-[M(?-L)]3 trimers (M = Ag, Au and L = monoanionic bidentate bridging (C/N~C/N) ligand). The research done is aimed to guide experimental chemists to make rational choices of metals, ligands, substituents in synthesizing novel organometallic electronic materials. Furthermore, the calculations presented here propose novel ways to tune the geometric, electronic, spectroscopic, and conduction properties in semiconducting materials. In addition to novel material development, electronic device performance can be improved by making a judicious choice of device components. I have studied the interfaces of a p-type metal-organic semiconductor viz cyclo-[Au(µ-Pz)]3 trimer with metal electrodes at atomic and surface levels. This work was aimed to guide the device engineers to choose the appropriate metal electrodes considering the chemical interactions at the interface. Additionally, the calculations performed on the interfaces provided valuable insight into binding energies, charge redistribution, change in the energy levels, dipole formation, etc., which are important parameters to consider while fabricating an electronic device. The research described in this dissertation highlights the application of unique computational modeling methods at different levels of theory to guide the experimental chemists and device engineers toward a rational design of transition metal based electronic devices with low cost and high performance.

This thesis continues the study into the synthesis and analysis of metal poly - yndiyl complexes. These molecules have shown promise as model molecular wires. The study provides a general overview of the interest in carbon based molecules and introduces the need for molecular electronics. Some of the most promising classes of molecular wires are described before outlining the methods of evaluation. / Thesis (Ph.D.)--School of Chemistry and Physics, 2006.

Thesis (Ph. D.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy in Chemistry." Includes bibliographical references (leaves 183-217).

Thermolysis of Cp*W(NO)(CH₂CMe₃)₂ (2.1) in halo, methoxy, or phenylethynyl-substituted benzenes leads to the formation of the alkylidene intermediateCp*W(NO)(=CHCMe₃) which selectively activates ortho C-H bonds of the organicsubstrates. The ortho-regioselectivity diminishes as the size of the substituent increasesfrom F (97 %) to C-=CPh (51 %). In the solid-state structure of all complexes the ortho-substituent is not coordinated to the metal centre; rather, the metal centre is engaged inagostic interactions with a neopentyl methylene C-H bond. Mechanistic studies on the chlorobenzene reaction reveal that the ortho-C-H-activation product is preferentially formed via thermal isomerization from the meta / para-C-H-activation isomers. Reactions between Cp*W(NO)(CH₂EMe₃)Cl (E = C or Si) and a variety of bis(allyl)magnesium reagents lead to the expected formation of Cp*W(NO)(alkyl)(allyl)complexes. Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCH₂) (3.5), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CMeCH₂) (3.6), Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7),Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) and Cp*W(N0)(CH₂SiMe₃)(η³-CH₂CHCHMe) (3.9) have thus been synthesized in moderate yields. The solid-state molecular structures of 3.5 and 3.7-3.9 feature a σ-π distorted ally! ligand in the endoconformation. Complex 3.5 reacts with pyrrolidine at RT to form Cp*W(NO)(NC₄H8)(CHMeCH₂NC₄H8) (3.10), a nucleophilic-attack product. Complexes 3.6-3.9 effect the concurrent N-H and α-C-H activation of pyrrolidine at RT and form alkyl-amido complexes analogous to the previously known Cp*W(N0)(CH₂EMe)(NC₄H₇-2-CMe₂CH=CH₂) (3.12). Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHMe) (3.7) at RT leads to the loss of neopentane and the formation of the η²-diene intermediate Cp*W(N0)(η²-CH₂=CHCH=CH₂) (A) which has been isolated as a PMe₃ adduct. In the presence of saturated organic substrates, C-H activation occurs exclusively at the methyl positions of the molecule. Reactions between intermediate A and unsaturated substrates lead to coupling between the coordinated η²-diene and the unsaturation on the organic molecule.Treatment of Cp*W(N0)(n-C₅H₁₁)(η³-CH₂CHCHMe) (4.1) with I₂ at -60 °C produces n-C₅H₁₁ I in moderate yields. Thermolysis of Cp*W(N0)(CH₂CMe₃)(η³-CH₂CHCHPh) (3.8) in benzene at 75 °C for one day leads to the exclusive formation of Cp*W(N0)(H)(η³-PhCHCHCHPh) (5.1).Trapping, labelling, and monitoring experiments suggest that 5.1 is formed via 1) the loss of neopentane and the generation of the allene intermediate Cp*W(N0)(η²-CH₂=C=CHPh), 2) the C-H activation of benzene resulting in a phenyl phenylallyl complex, and 3) the thermal isomerization of this latter species to 5.1.